Antitumor Effects of Collagen Peptide Nanoemulsion and Nanoliposome Prepared from Taiwan Tilapia Skin in a Mouse Model.

Globally, cancer has emerged as a major cause of human death, and the traditional therapy suffers several drawbacks such as poor survival rate, potential side-effects and increased drug resistance. Recently, natural bioactives obtained by valorization of food and agricultural wastes have drawn great attention as a promising alternative cancer therapeutic. This study aims to evaluate the antitumor efficiency of low-molecular-weight collagen peptides (TSP) isolated from Taiwan tilapia skin, as well as their nanoemulsion (TSPE) and nanoliposome (TSPL) without or with folic acid-chitosan (FC) ligand conjugation (TSPE-FC and TSPL-FC) in comparison with paclitaxel using a nude mice model. Based on the optimized enzymatic hydrolysis conditions, TSP was prepared using alcalase 12.5%, sample-to-water ratio 1:30 (w/v), pH 8, temperature 50 °C and hydrolysis time 6 h. TSP containing a high proportion of 172 Da fragment (48%) and hydrophobic amino acids (67.2%) was subsequently incorporated into two nanoformulations, with TSPE being prepared with an optimal ratio of soybean oil, lecithin, glycerol, Tween 80 and deionized water, while TSPL was prepared with ethanol, cholesterol, phosphatidylcholine, Tween 80, glycerol and deionized water. The mean particle sizes of TSPE and TSPL were, respectively, 16.1 nm and 33.9 nm, which changed to 15.2 nm and 35.3 nm upon FC conjugation, along with a shift in zeta potential from negative (-41.7 mV for TSPE and -46.6 mV for TSPL) to positive (+23.2 mV for TSPE and +23.9 mV for TSPL), which is favorable for tumor cell penetration and uptake. Nanopeptides showed a sustained release of TSP in an in vitro release study compared to a rapid release from nonencapsulated TSP. Following treatment of A549 cell-induced nude mice tumors with TSP, TSPE, TSPL, TSPE-FC and TSPL-FC at two different doses (100 and 300 mg/kg body weight (BW)) as well as paclitaxel (15 mg/kg BW), the tumor volume, respectively, decreased by 22.4-43.3%, 40.4-70.6%, 36.9-69.2%, 59.1-78.6%, 71.5-85.7% and 90.9%, while the tumor weight reduced by 18.2-48.0%, 42.6-73.0%, 36.1-69.6%, 58.8-79.5%, 69.6-85.2% and 90.3%. In addition, a decrease in the levels of epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) were shown in mice serum for all treatments, with paclitaxel being the most effective in inhibiting tumor growth, followed by TSPL-FC/TSPE-FC, TSPE/TSPL and TSP. Collectively, both nanoencapsulated peptides and FC conjugated nanopeptides showed the most pronounced effect in inhibiting lung cancer tumors in mice.